Crystallization observation

Overney R, Howald L, Frommer J, Meyer E, Brodbeck D and Guntherodt H 1992 Molecular surface structure of organic crystals observed by atomic force microscopy Ultramicroscopy 42-A4 983... 

Heiland W and Taglauer E 1973 Bombardment induced surface damage in a nickel single crystal observed by ion scattering and LEED Rad. Effects. 19 1-6... 

Ivanov, D.A. and Magonov, S.N., Atomic Force Microscopy Studies of Semicrystalline Polymers at Variable Temperature, in Polymer Crystallization Observations, Concepts and Interpretations, Sommer, J.-U. and Reiter, G., Eds., Springer, Heidelberg, Germany, 2003, chap. 7. 

For the study of the M dependence of I and V of FCCs, film samples (0.1 mm thick) were isothermally crystallized from the melt into the orthorhombic (= ordered immobile) phase at atmospheric pressure. The range of AT was 10 -15 K. In order to observe isolated single crystals, observation was limited to the earlier stage of crystallization. 

Experimental structural data are available for two crystalline derivatives of c/s,cis-cyclo-octadiene-1,5 (86). The distorted-boat form occurs in both crystals (observed C—CH2—CH2—C torsion angles 65 and 74°, respectively). Hedberg and Hedberg have performed a gas-electron diffraction study and found that the distorted boat conformation predominates also in the gas-phase (87). For the dibenzo derivative, however, there are crystallographic indications that in the solid state the eight-membered ring has the chair conformation (88). 

In recent years, stereochemistry, dealing with the three-dimensional behavior of chiral molecules, has become a significant area of research in modern organic chemistry. The development of stereochemistry can, however, be traced as far back as the nineteenth century. In 1801, the French mineralogist Haiiy noticed that quartz crystals exhibited hemihedral phenomena, which implied that certain facets of the crystals were disposed as nonsuperimposable species showing a typical relationship between an object and its mirror image. In 1809, the French physicist Malus, who also studied quartz crystals, observed that they could induce the polarization of light. 

Reiter G, Castelein G, Sommer JU (2003) In Sommer JU, Reiter G (eds) Polymer crystallization, observations, concepts and interpretations. Springer, Berlin Heidelberg New York, p 131... 

In this study, D-SCMC seed crystals were put in a racemic SCMC supersaturated solution in a batchwise agitated vessel and growth rates in longitudinal and lateral directions and the optical purity of D-SCMC crystals were measured. The growth rates and optical purity were discussed considering surface states of grown crystal observed by a microscope. The kinetics of crystal growth were measured and a model of inclusion of impurity was proposed. 

Figure 11.4 shows the various Habitus of calcite crystals observed in nature. To demonstrate Habitus changes at different orders of crystallization, or those depending on crystallization temperatures, three examples of intergrowths of two different Habitus of calcite are shown in Fig. 11.5 [3], see also Fig. 7.10. Figure 11.5(a) shows that later-grown calcite crystals on earlier-formed prismatic crystals of calcite show a different prismatic to a dog-tooth Habitus from the host crystal. 

The structure of kemite consists of parallel infinite chains of the [B40 (0H)2]2,/ n ion (6) composed of six membered rings (80). The polymeric nature of the anion is consistent with the slow rate of dissolution and crystallization observed for kemite. 

This led them to conclude that there is free rotation about the C—O bond in the nitrate. It also indicates that the shortening of this bond in crystals observed by... 

Prasang C, Whitwood AC, Bruce DW (2008) Spontaneous symmetry-breaking in halogen-bonded, bent-core liquid crystals observation of a chemically driven Iso-N-N phase sequence. Chem Commun 2008 2137-2139... 

Implantation of optically pumped beams in a crystal-observation of asymmetry asymmetry of radiation Li first data taking Oct 85 [BON84]... 

Figure 18. DSC aspects of gradual polymorphic transition of the deposited crystals observed during crystallization of racemic NPMe3 from EtOH (a) y-form, (b) a mixture of y, 5 and r -forms after 8 days, (c) a mixture of r and E-forms after 13 days, and (d) a mixture of r and -forms after 19 days. (Reprinted with permission from ref 18. Copyright 2003 American Chemical Society.)...

Industrial Pt-Sn catalyst studied. Sn is dissolved in Pt forming a solid solution at low Sn concentrations. Sn crystallities observed at higher concentrations.50 ... 

J. Needham, Lu Gwei-Djen, The Earliest Snow Crystal Observations. Weather 1961, 16, 319-327. 

Fig. 4.1 An illustration from the original paper by Lehman (1877i>) on Physical Isomerism showing his hot stage microscope and various shapes of crystals observed. Another noteworthy feature of this figure is the time vs temperature cooling curve for ammonium nitrate in the upper left hand comer, showing four inflection points that indicate polymorphic transitions. (Reprinted by permission from Zeitschrift fur Kristallographie.)...

It is significant not only to note the numerical trends of the thickest crystals but also those of the thinnest crystals d ,j as a function of undercooling (Fig. 15). In this case a linear relationship is obtained. This finding substantiates the conclusion that the thinnest crystals observed in the micrograph (after subtraction of the known distribution formed on quenching) represent the original nuclear size, whilst the remaining crystals have thickened isothermally. 

Spectra of Crystals Infrared Dichroism. The spectrum of a single crystal observed in polarized light depends upon the orientation of the crystal axes relative to the plane of polarization. A similar situation exists for macroscopically oriented high polymers, obtained by extruding or stretching polymeric materials such as nylon, polyvinyl alcohol, and polyethylene. Ellis and co-workers were the first to make systematic studies of IR dichroism in H bonded systems (604, 779, 780). Further attention was drawn to the method by Mann and Thompson (1334), Crooks (463), and Ambrose, Elliott, and Temple (595, 38, 589, 4). 

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